System of automatic anticipatory control



"Feb. 16, 1937.

A. S. REYNOLDS SYSTEM OF AUTOMATIC ANTICIPATORY CONTROL Filed March 18, 1935 4 sheets+s h eet 1' A. REYNOLDS.

" Feb. 16, 1937;

SYSTEM OF AUTOMATIC ANTICIPATORY CONTROL.

Filed March 1 1 935 4 Sheets-Sheet 2 I M/l Z/w aza Feb. 16, 1937. A. s. REYNOLDS 2,071,142

' SYSTEM OF AUTOMATIG ANTIGIPATORY CONTROL Filed March 18; 955 4, .r$he's-Sheet s Maw.

1937- A. s. REYNOLDS 2,071,142

SYSTEM OF AUTOMATIC ANTIEIPATORY CONTROL Filed Mroh 1a, 1933 4 Sheets-She et 4 Patented Feb. 16, 1937 UNITED, STATES PATENT- "OFFICE v SYSTE OF AUTOMATIC ANTICIPATORY CONTROL 7 Anita S. Reynolds, Princeton, N. J. Application March is, 1933, Serial No. 6 1,451

- 23 Claims.

. or desiredstate could be automatically. anticipated in order that ,thecorrective means could be applied at atime and rate such that excessive departures would be avoided; also when the departure has been checked and the trend started towards 7 normal, to so change the corrective means as to anticipatethe arrivel at a normal or desired condition. In otherv words, to introducein mechanical form the equivalent of the actions of a well trained operator who by watching indicators,- could take account of. the various rates, time intervals. and, ,amplitudef'of' movements and apply and remove the corrective meas- 1 ring or about to occur, concerning which an opures in such manner asto anticipate the changes, thereby maintaining a closer-control. In my pending application No.- 620,143, I have shown means fortaking account of both the rate and the amplitude or extent of deviation from normal and making a correction in accordance with the combination of these factors; Also, in my Patent No vl,85 l,596,I have shown means for adding a factor to the correction which represents thelag; also to make, a faster movement on the reversal of thetrend in returning to normal. I

In the present invention, Ihave combined these improvements in one mechanism in such mannerthat not-only isthe rateand total deviation combined in determining'the amount of needful correction, but also there is provided means for automatically altering the rate and timeof applying and removing the corrective actions de-.v pending upon the directionand amplitude of deviation and the rate of change towards or away from the normal. V

The combination of all these factors makes it possible to do mechanically what an operator could do by the exercise of experience and judgment. I In some operations this arrangement will take account of certain conditionswhich are occurerator could have no knowledge.

In a control operation it is often desirable as the factors change resulting in a movement away from normal or the desired state-, to apply cor-, rective measures at a relatively high or rapid rate in, order to check and reverse the trend before it shall have gone too far. It is also desirable in some control preblems'and under certain conditions to change the rate'of application of the corrective measures at certain periods of the control cycle. These changes may be from a higher to a lower rate or from a lower to ahigher rate. The changesmay be required while the trend is continuing in one direction orzupon the .reversal of the trend or upon an approach to the reversal. vIt is a feature of my invention to provide automatic means 'for accomplishing these results with the object of anticipating the departure from and the approach to a desired condition and thereby prevent the wide, swings so v detrimental to many;of the presentday processes and operations.

Broadly speaking, existing measuring or control systems consist of an indicating or testing device which determines the amount of deviation, and a control device which is automatically ad- I justed in accordance with the operation of the testing device. For purposes of simplification,

, I designate the first' of the above mentioned functions or devices as theinput and the second as the output.

In eflect, one of the features of this invention consists in providing between the testing mechanism or input and the control mechanism or out put, whether it be controlling heat, pressure or any other physical conditioma number of transvide means for making certain of these cams;

active for moving the output to the exclusion of th others and thus cause the ultimate control to which it-isclutched. The order of attachment and detachment may be determined by the direction of rotation or movement of the input, by the function in a manner best suited to the changing all in an order as determined by the particular medium under control.

For engaging and disengaging the rods, I have illustrated both electromagnetic and mechanical clutching means. It is to be understood, however, that the invention is not limited to any of the forms of clutches shown, as any suitable type may be employed without departing from the spirit of the invention.

The objects of this method are several, one being that by translating the movements, I can add to or subtract from the translation, a certain amount which will represent the lag of the system. Another is that I can by this means anticipate and thereby prevent abnormal changes. Still another object is that by this means, I can depart from the old and well-known position control wherein there is a fixed phase or step relation between the condition of the testing and the control adjusting agencies. In other words,'by this means, I provide a flexible or floating mechanism which automatically adjusts itself to changing conditions, allowing the testing mecha nism to arrive always at a balance at the predeterminecl position, but permits the control adjust ing mechanism to assume an independent position not necessarily in phase with the testing.

In the illustrated example of my apparatus, I have chosen a common and well-known type of inputand output. Some of the-parts and their mode of operation are disclosed in prior Letters Patent of the United States to Leeds No. 1,125,699, my invention comprehending but not being limited to their employment.

My invention is applicable to any type of con-' trolling or measuring system for physical, electrical or chemical quantities, irrespective of the form of the indicating, or controlling mechanism. Thechoice of the controlling or indicatingmechanism will depend upon the nature of the scientific or industrial problem to be solved. 7

For example, it may be employed where it is desirable to have the mechanism in constant engagement with the input and to have periodic engagement with the output as illustrated in Fig. 3 of my pending application 620,143.

It may equally well be employed where the testing is periodic and the engagement with the output is also periodic as in Fig. 2 of pending application No. 620,143. -It may also be employed where the testing is periodic and the engagement with the output constant as in Fig. 1 of this application.

It will be observed, therefore, thatmy'invention may be applied to any of the existing types or methods of control or measurement. It is also equally applicable whether the movements of the input and output are rotary or rectilinear.

Since I employ cams for'translating the movements of the input and since many of the existing devices are of the rotary type, which may require more than one revolution of the cam, I have devised a new type of spiral cam which operates in a similar manner to the well-known but limited motion, heart-shaped cam for translating a rotary movement into a rectilinear one. Such a cam obviously can be rotated only a part of a complete revolution in either a clockwise or a counter-clockwise direction, since to rotate further would cause the two cam surfaces tocross and interfere with the free movement of the'rider.

It is a feature of my invention to provide for this condition by a new type of spiral cam com--- 'posed of two separate parts each mounted in a difierent plane and employing a double ended out of engagement with the clockwise section and at this time the second half of the rider goes into engagement with the counter-clockwise section. By this means I am not limited in the number of revolutions or in the length of rectilinear movement possible for the rider.

' In any control apparatus each and every movement of the input must be followed by a movement of the output. Therefore, it will be observed that the common forms of spiral cams, either of the.disc or drum type, will not be suitable for this purpose as the tracks lie in the same plane and a shuttle shaped rider must be used to prevent following the wrong groove at a point of intersection. The use of this type of rider necessitates a sectionof groove at the position of reversal or at the position where the rider changes ,1 from one to the other of the different grooves, in

which therewill be angular movement without a corresponding rectilinear movement. It will be noted that I obviate this difliculty by placing the two grooves in different planes and that there is, therefore, no position of angular movement without a resultant rectilinear movement. 1

The variouscams illustrated may be similar as regards rate or slope, or they may be dissimilar as conditions may require.

In my Patent No. 1,851,596, I have shown means for adding a correcting factor to compensate for lag in a system. This is a single means, self-actuating in that the compensation is accomplished by the movements of the testing mechanismfwithout the aid of another source ofpower or mechanism extraneous to the instrument.

In my present invention, I have introduced a plurality of means, all internal to the mechanism but separate and distinct,.one from the other, and all operated by the movements of the instrument without the aid of a separate source of power.

For the purposes of this application, I have illustrated several'forms of the invention as applied to a conventional type of heat responsive and control mechanism. It is to be understood, however, that the invention is-not limited to any of these forms of mechanisms, or to the control of temperature or pressure only, or to the particular type of input referred to. It is applicable to any type of controlling or measuring system for physical, electrical or chemical quantities, irrespective of the form the input or output may assume, and to any of the existing forms of indieating or controlling mechanisms. 'The choice of the controlling or indicating mechanisms, the type of input and output, and the magnitude of the rate of anticipatory control desired will depend upon the nature of the problem to be solved.

In one embodiment of my invention, for example, Fig. 1, I interpose between the input (I) and the output, a mechanism consisting of the following parts: 7 i

A first part comprising a cam specially cut in accordance with the needs and nature of the particular elements under control. Each cycle of operation that a deviation occurs, this cam is" rotated clockwise or counter-clockwise by the input, its position representing the total devia tion.

A second part comprising a plurality of cams cut with varying degrees of slope in accordance with the needs and nature of the particular processes under control, to add a rate factor to' the total deviation factor of the first part.

' v A third part comprising a pair of clutch elements, one attached to the total deviation cam and the other attached to the plurality of rate cams, the purpose being to cause thelatter cams to be displaced i unisonwith the total'deviation cam.

' In'the cutting of all of the cams, provision can be made for the lag of the entire system, for

required anticipation, and for the nature of the elements under control. f A fifth part comprising a movable structure slidably associated with rods connecting with the riders engaging the plurality of cams noted in the second part. Embodied in this structure is a clutching means to enable any one of the said rods to be selectively engaged with the structure in order that the latter may move inunison with the selected rod. I

A sixth part comprising a lever arm; one end i: of which is attached to the out'put,the other end being attached to the structure-described under the fifth part above, the central portion of the lever arm being attached to 'arodhaving'a rider engaging with the cam under the first part noted above. This lever moves the output in accordance with the result of the combined movements of the first and second parts. The extent of this I final movement of the output is therefore the result of a combination or integration of first, the amount of the anticipatory control required according to the total deviation, and'second, thev amount required in accordance with the number of degrees of change in one unit of time This part may be termed a. mixer or an integrating lever or bar, since it isused for combining or integrating the movements "of the first'and second parts. I

' I under'the first part may be replaced by two or.

I more suchcams as are described under'the sec-" 0nd part also operating through rods to move allowed to operate directly on the output.

this construction I have shown both fast and slow cams with the riders attached to rodswhich pass' For ,somepurposes. the single cam described another member similar to the structure described under the fourth part. I In Fig. 2, there is shown a simpler' form' of my invention in which the integrating feature has been dispensed with and the traveling structure In ture in order to indicate the possibility of chang-' ing the rate invarying degrees and at various times during the cycle of operations.

Fig; 4 is an end view of the structure shown in Fig. 3.

Fig. 5 is ,a sectional view of the same structure.

Fig. 6 is a side elevation on the line 6-6 of Fig. 3 showing the cam 83.

Fig. '7 is a similar view on .Fig. 8 is a side elevation on an enlarged scale A fourth part comprisinga'resto'ring meansfor returning the rate cams to normal position during each cycle of operation. I

slide freely through structure 25.

. clutching the rods to the structure. I

the line 1-'I of Fig. I 3 showing the cam 82. I I I of the spiral cams which can be used to replace any of the illustrated cams such as Figs. 6, 7,

etc. I

Fig. 9 is an end view of Fig. 8.

Fig. 10 is a plan view of the shifting rider arm.

Fig. 11 is a sectional view of ,the three cams and the clutch plates illustrated in Fig. 1. Fig. 12 shows a-means of operating the rod and cam selecting means. I v Fig. 13 is a view showing a valve in place of a rheostat.

I Fig. 14 is a schematic view showing the direction of movements of the various rods illustrated in Fig. 1, when greater movements are required such, for example, as, with the spiral-cams of I Fig. 8. a Fig. 15 is a schematic view showing thecombination of a plurality of the mechanisms illus- I trated-in Fig. 1, operatingan integrating mechanism as described hereinbefore under the 6th part. I I

Referring'to Figs. 1 and 11, the input mechanism illustrated by the box I moves the cam III .which, with the clutch member I5 attached, is

pnned to shaft I2. Traveling in the grooves of I0 is the rider I3, the latter being attached to rod I4. Rotatably mounted on the shaft I2 is the sleeve II. This sleeve has mounted on it clutch member and cams I1 and I8. Sleeve II, with clutch member 20 and cams I1 and I8, can also be moved a sumcient amount longitudinally along theshaft I2 to permit engagementand disengagement of clutch members I5 and 2.0. This lonv gitudinal movement is caused by the forked member 44 engaging with .the annulargroove on the "endofII.

Operating in the grooves of I cams I8 and I! are the riders 2| and 22 which are attached to the sliding rods 23 and 24. These latter rods normally Mounted in 25 in position to engage either of the two rods 23 and 24 are two clutch magnets 5| and 5|].

The central portion of lever 3i is pivotally mounted on one end of rod I4. The lower end of 3| is pivotally attached to one end of the arm 30, the other end of being attached to structure 25. 2 On the upper end of '3I there is pivotally mounted a link 32 which is attached-to chain 33 passing over idler 34 and engaging with-sprocket 35. Attached to'35 is the rheostat 36 the adjust- I ment of which is the end to be accomplished.

Mounted on the end of shaft I2 is the rheostat 53 which is associafed with the potentiometer circuit illustrated in Fig. 2.

The timed control shaft 4! is driven by a chain 48 engaging with sprocket 49. 'I'hechain 48 also engages with a timed sprocket-(not shown) which may be in the input I or operated by any other convenient means. The object of this is-to .pro-

vide for the functioning of the apparatus. during the same time intervals employed in the testing or input mechanism. Shaft 41 carries two cams and 4| which serve to restore the sleeve II by means of arms 42 and 46 after II has been m tated through the medium of clutch members I5 and 20.

Shaft 41 alsohas pinned to'it cam which engages on each cycle of operation with the forked I member 44. Itwill beseen in the sectional view, Fig. 11, that the cam III, with its associated clutch member I5, is pinned to shaft I2. Sleeve I- I rotates freely on shaft I2. but has in addition a short longitudinal movement sufiicient to engage and disengage I5 and 20. Clutch member 20 and cams I1 and I8 are rigidly connectedto sleeve II.

Fig. 2 shows a simpler form of the invention useful under certain conditions, in which I make use of the total deviation but not the rate or the integration of the total deviation and rate. I have therefore dispensed with the rate cams and the integrating lever 3I. In this embodiment, the input mechanism indicated by the box I rotates the 1 shaft I2 and the two cams I1 and I8 which are 'the magnetic material rods 24' and 23 inorder.

pinned to the shaft. The rider 2I attached to rod 23' travels in the groove of cam I8 and the rider 22 attached to rod 24' travels in the groove of cam I1, 1

Normally sliding freely on rods 23 and 24' is the movable structure 25' and mounted inside 25' are the two clutch magnets 50' and 5I'. magnets are arranged when energized to clutch that structure 25 may be moved longitudinally by either of them.

Mounted on 25 is an extension 52 which is at-' grammatically at F and for simplicity of .illustration, the rheostat 36 is shown as increasing or decreasing the flow of current through the heating unit. It is obvious that any of the wellknown heat changing arrangements may be operatd by the rotation of 36.

The usual method of measuring the temperature of the furnace by means of a thermocouple is "illustrated in Fig. 2. The electromotive force produced by the'thermocouple I in the furnace F is balanced against the potential difference between the end I of the resistance IOI which is V on the circumference of the rheostat 53" and the sliding contact I06. This potential difference across the resistance IOI is maintained constant by a potentiometer circuit consisting of a battery I02, fixed resistance I03, and adjustable resistance I01 which is provided toregulate the battery current to the desired value.

couple I00 equals the potential difference produced between the point I05 of the resistance IOI and the sliding contact I06 by the potentiometer circuit, no current will flow in the galvanometer I04. When a difference exists between the electromotive force of the thermocouple I00 and the difference of potential between the point I05 of the resistance IOI and the sliding contact I06, a

current will flow through the galvanometer in a direction depending upon whether the electromative force of'the thermocouple is greater or less than the difference of potential between the point I05 of the resistance IM and the sliding contact I06. The deflection of the galvanometer needle causes a rotation ofthe shaft I2 to adjust the sliding contact I06 until a balance is again established. As shaft I2 rotates, box 25 is moved which rotates rheostat 36' by means of extension 52, cable 33. and pulley 35'.. Rheostat '36 ad justs the current from source I I0, contact I09 adjusting resistance I08 to heating element I II which changes the temperature of furnace F.

A similar thermocouple and potentiometer arrangement may be employed for Fig.1.

The

When the electromotive force of the.thermo-' Itis to be noted in connection with Fig. 2, however, that since the balancing rheostat 53 is pinned to shaft I2, it will always return to the same position when the temperature is balanced, but 'since control rheostat 36' is not directly associated-with 53 but is moved independently at varying rates caused by the cuttings of cams I1 and I8, moving rods24 and 23', and through them structure .25, 36! may assume a position toproduce a flow of heat that will cause the balancing, which position may or may not. be the sameat all times due to varying conditions in or surrounding the furnace. This is an important feature; of the invention.

Referring to Fig. 3, it will be noted thatthe ,two cams I! and I8 have been replaced ,by four cams .00, 8I, 82 and 83, all mounted on shaft I2. These cams, through their riders, operate rods 84, 85; 86 and 81. The object of thisis to illustrate a means by which the control can be shifted from one channel to another as occasionmay require a change in the rate of applying the corrective measures.

The end elevation, Fig, 4, shows the rods 84,

85, 86 and 81 arranged in circular formation around the shaft I2 in order that the engaging shaft 26 may rotate a clutching cam 88 so as to enable the structure 25 to become attached to any one of the four rods asconditions may require. I n

Fig. 5 shows a sectional view of-structure 25 on the line 5-5 on Fig. 3 to indicate how a rotation' of 26 revolves cam 88, causinglatch' spring 89 to engage with one of the four rods which are all provided with fine teeth or serrations on one edge- There isa latch spring similar to 89 associated with each of the four rods.

7 26 is a square section shaft sliding freely in cam 88 andbearings 90and9I, which latter rotate freely in structure 25. It will therefore be observed that a rotation of 26 one step in a clockwise direction willcause projection 92 on cam 80 to engage with spring89, causing the, latter to engage with theserrations on rod 85, causing the structure 25. to become clutched 'torod 85 and to move at the same rate as 85 moves. A counter-clockwise movement of one step will f cause 92 to engage spring 94 to rod 86.

. Two clockwise steps will cause projection 95 to engage spring 96 to rod 81 and two counterclockwise steps will cause projection 91 to engage spring 98 to .rod 84. It will therefore be seen that by the direction of rotation of 26 and the number of steps taken, the structure 25 may be clutched to any one of the four illustrated rods and that 25 will then be moved at a rate as determined by the slope of the cam associated with that particular rod. 1 V

Fig. 12 illustrates a means by which the square shaft 25 maybe stepped around to select any one of the four rods. The stepping may be caused by any suitable means such, for example, as a timed mechanism operating gear 31 or by the condition of the medium under control.

As noted above, any one or all of the cams illustrated in Figs. '1, 2 and 3 may be replaced by a pair of spiral cams for such conditions as may require a greater angular movement or rotation than is permissible with a simple disc type cam. A pair of such spiral cams are shown on an enlarged scale in Figs. 8 and 9. V

. Referring to Fig. 8, cam I0 isillustrated as having a comparatively steep slope, while its mate,

cam II, is illustrated as having a slope of lesser I degree. The rod 12, which is operated by this pair of cams, is mounted between them and has a double headed'rider 13 attached to a pivoted lever arm 14 which is pivotally mounted on rod 12 by the screw 15. r

The double headed rider 13. is provided withan enlarged section on each of the two ends in order that once engaged with. the groovein either cam, it cannot become disengaged until ready at the central point (Fig. 8) to engage with the other groove. If the cams Illand 1| ,rotateon orwith shaft |2 in a counter-clockwise direction, the section 16 of .13will travel into the groove 11 of eam1l and as the latter recedes because of the spiral, away from the center arm 14 will be drawn to one side,;as shown in Fig. 10, so that the other end 18 of 13 will be traveling out of the path of cam 10 andwill" not interfere'with the latter where the two cams cross each. othersv path. This operation will cause the rod 12 to be moved towards the left} hand.

Upon a reversal of direction of rotation, 12 will be moved towards the right and upon reaching center, as shown in Fig. 8, a further rotation in a clockwise direction will cause section 18 of rider 13 to enter the groove 19 of cam 10, and rod-12 will continue to be moved towards the right hand. The terms right and left hand are used with reference to Fig. 8.

The continued movement of the cams will cause rider 13 to be drawnto thejside'opposite to that shown in Fig. 10, so that section 16 will travels are required, when the integrating lever 3| may be tilted too far for satisfactory operation of the output. Under such conditions, the plan shown schematically in Fig. 14 may be employed;With this arrangement, since the rods move under .ordinary conditions in the same direction, a greater longitudinal movement of 3| may take place without excessive tilting. The embodiment shown in Fig. .15 is an arrangement wherebyseveral factors governing the conditionv of a medium under control may be taken into account to automatically move the outof the output dependent on the condition of two put. For example, in certain chemical operations, it maybe desirable to make the final movements 5 or more separate and distinct mediums.

final integrating lever 56 which moves the"output 51. In this manner, it willbe observed. that In this arrangement, the two separate integrating levers 3|a and 3|b are each operated in a manner similar to that described for Figs. 1 and 14. Their movements are then'transferred to the the movement of the output is the integration or resultant of several changing conditions. It is I obvious that this arrangement may be extended further to include a plurality of primary movements afiecting the resultant movement.

I have shown only sufficient mechanism to 11- lustrate the principles involved and have omitted 7 such parts as are not definitely required to enable one skilled in the artto understand the functions and operation of the devices.

It is to be understoodthat in the several illustrations, the conventional forms of cams, riders, drive, clutching mechanism, etc-., are shown merely toillustrate certain embodiments of the invention and that these details, as well as others, may, be varied without departing from the spirit of the invention as defined in the claims.

The operatioriof the" embodiment illustrated in Figs. 1 and 11' is as follows: Assuming that the mechanism contained in the input I is arranged torespond to temperature changesas described in detail'in Patent No. 1,125,699, a decrease in temperature in, for example, a furnace: (not shown) will cause' a counter-clockwise rotation of cam l0. At this time spring 43 will be pulling forked arm 44 and sleeve towards cam l0, thus causing engagement of clutch member 20 with,

clutch member i5. f Therefore, clutch member 20, sleeve H, and cams l1 and 18 will also be rotated in .a counter-clockwise direction. During this period of the cycle of'operatlon, shaft 41 is in a position such that cam 45 is out of engagement with arm 44 and cams and 4| are out of engagement with arms 42 and "46. The counterclockwise rotation of sleeve II will raise arm 46 towards cam 4|, at the same time lowering 42.

, The rotation of cam l0 will cause a movement towards the right of rod I4 because the rider I3 is traveling in the groove of cam ID. .This movement of rod 4 will move the upper part of arm 3| to the right. v Since cams l1 and I8 are rotated in a. counterclockwise direction, rods '24 and 23, by 'means of their riders 22 and 2|, will be moved to the left. i

The rotation of cam III also rotates the instilated contact wheel 6|, causing contact 55 to close, energizing clutch magnet 5|ffom ground 63 throughwires I9 and 54, and normally closed contact Iii-to battery 62. a

The energizing of clutch magnet 5| engages the traveling structure 25 with rod 23 so that as 23' moves to the left due to the rotation of, cam I8, structure 25 will be moved at the same rate. Since 25 haspivoted'to it one. end of arm 30, the other end being attached to lever, 3|, the lower part of 3| will be moved to the left, giving theupper end a movement additional to that given by ro'd l4 under control of cam IO. 7 The result of these-combinedmov'ements serves to rotate 1 rheostat36 to increase the heat.

During the operation just described, shaft 41 has been rotating in a counter-clockwise direction viewed from the end marked 41. ,Cam 45 now engagesarm 44, openingcontact IE to release ,clutch magnet 5|. This action draws sleeve towards rheostat 53, thus disengaging clutch members l5 and .20." Further rotation of shaft 41 causes cam 4| to engage arm "46 to restore sleevell .with cams I1 and i8, and clutch member 20 to normal angular position. During this operation, since magnet 5|. is deenergized, rod 23 will slide a freely, through structure 25, allowing the latter and the output 36 to remain stationary .until the next cycle occurs.

I "The functions performedby the movements described are as follows: The cutting ofcam Ill represents the total deviation while the cutting of cams IIand l3 represents the rate of deviation, since shaft 41 is driven .by the chain 48 from a timed source of power either in the input I or separate from it as desired. The total movement of lever 3| is transmitted through arm 32 to chain 33, sprocket 35 and finally to the input rheostat 36 which controls the input,of heat to a furnace (not shown in this view) which is the medium under control. Therefore, the rheostat .36 will be moved a certain amount in accordance with the totaldeviation and an additional amount for the rate of deviation.

Assuming now that the correction that has taken place is of sufficient magnitude to cause a reversal of the movement of the input I, during the next cycle of operation cam Ill will be rotated in a clockwise direction, moving rod I4 to the left and rods 23 and 24 to the right. The change of direction of cam ID will rotate wheel 6| in a direction to open contact 55 and close contact 66, thus energizing clutch magnet 50, so that the movement of structure 25 will now be under control of cam 1. Under conditions where it is desired to move the output at a faster rate on its return to a normal position than it has been moved away from normal, the cutting of cam l1 will be such that structure 25 will be moved back more rapidly than it was moved away from its normal position. Should the contrary condition be desired and a less rapid return movement be desired, the cutting of cam I 1 will be such that structure 25 will be returned at a slower rate than the rate at which it originally moved away from normal. It will therefore be seen that by varying the slopes of the rate cams l1 and I8, the rate factor may be applied to the example, the direction of trend of the deviation. What has been described above is a condition where a decrease in temperature in the medium under control has occurred and it has been desired to raise the influx of heat to compensate for this decrease. Should, however, the reverse condition occur and an increase in temperature of the output be encountered, then the operations' would be the reverse of those described above. Starting from a normal position, cams l0, l1 and I8 will be moved in a clockwise direction ,'raising arm 12 towards cam 40; moving rod l4 to the left androds 23 and 24 to the right, energizing magnet 50 to engage structure 25 with rod 24. These combined movements are transmitted to lever 3| and to output 36 to reduce the heat.

The continued rotation of shaft 41 now causes 1 cam 45 to engage forked lever 44, sliding sleeve II in a direction to disengage clutch members l5 and 20, at the same time opening contact I6 anddeenergizing clutch magnet 56. This action frees structure 25 from rod 24. Continued rotation of shaft 41 causes cam 4| to engage arm 46, rotating sleeve ll, cams l1 and I8, and clutch member 20 back to their original positions. This action has not disturbed theposition of 36 because of the deenergizationof magnet 5|.

Now assuming, forexample, that the action described is the equivalent of one degreechange in one unit of time and that several such small changes to a total of 5 take place in 5 succeed ing units of time, the rheostat 36 will have been moved away from its starting position an amount equivalent to thetotal deviation and the summation of the several rates of deviations.

The slope of the cams l1 and I8 is such that i had the first movement been a relatively greater deviation in that one unit of time, say for example 5 degrees, there would have been a greater total movement of rheostat 36, thus taking into account the more rapid change that had taken place and giving a greater movement of the output on that account.-

The important point tobe noted in all of the 75 operations described is that when a deviation output at different speeds, depending upon, for

occurs, the total deviation cam ID, with each cycle of operation, is moved in the direction of trend and remains in that position until the next cycle of operations. The two rate cams H and I8, however, will bemoved away from normal to add their movement to structure 25 and thence througharrn 30 to lever 3| and the final output 36, but after each such movement, 25 is released from engagement'with either of rods 23 or and these rods, together with cams l1, and I8, are restored to their original positions.

The operation of the-embodiment shown in Fig. 2 is as follows: Upon a decrease in temperature in the furnace F, the shaft l2 will be rotated in a counter-clockwise direction by the operation of the input contained in box I. The rotation of rheostat 53" rotates by friction the insulated contact wheel 6|, causing contact 55' to close, completing a circuit from battery 62 through clutch magnet 5|, contact 55 to ground 63'.

The energizing of 5| clutches rod 23' to the structure 25. The rotation of l2 rotates the two cam structures l1 and I8, causing the two rods 24' and 23' to be moved to the left. The rider 22' attached to rod 24' will travel in the groove 64 of cam l1 and the rider 2| attached to rod 23' will travel in the groove 65 of cam l8. Since 65 is more steeply sloped than 64, rod 23' will move to the left at a faster rate than will rod 24'.

During the operations just described, arm 52, attached to 25 and acting through chain 33', hasrotated rheostat 36' in a counter-clockwise direction through a greater angle than the balancing rheostat 53' has been rotated. This movement. of 36 serves to increase the flow of current in the furnace F. Assuming now that several cycles of operation are required before rheostat 53' brings the potentiometer circuit into balance, it will be observed that 25' will have beenmoved to the left a greater'distance than rod 24'. "I

The furnace having now risen in temperature to the point where a reversal takes place, 53 and 6| will reverse their direction of movements, opening contact'55' and closing contact'66'. This action deenergizes clutch magnet 5| and energizes clutch magnet 50, disengaging rod 23 from structure 25' and engaging rod 24".

Assuming that the change in the furnace requiring more heat is of such a nature that more heat is continuously required for-a certain period, then the condition just described may remain constant for a period requiring nofurther change in the supply of current. When the time arrives that less heat is required, structure 25' will be moved to the right at a lower rate than it was first moved to the left, since it is now clutched to rod 24' which is being moved by groove 64 which has a less steep slope than groove 65 moving rod 23'. It will be seen, therefore, that if the conditions causing'the original change as described require continuously a greater supply of heat, then the rheostat 53' may return to its original position, but the current supply rheostat 36' may be left in a more advanced position.

If the original movement was caused by an increase in temperature, then the reverse of the operations first described would take place. Shaft I2 would rotate in a clockwise direction, energizing clutch magnet 50', engaging rod 24' and moving structure 25' to the right at a faster rate than the movement of rod 23. It will thus be seen that in the various movements necessary to establish a proper balance, the-control rheostat 36 does not necessarily remainin stepv with-the ii. The method of temperature control which consists in producing upon-a departure from a desired normal an effect which is a function of the rate of temperature change, 0i.v the departure of the temperature from a predetermined magnitude and the increment of lag of said departure, controlling by'said effect the appli'cation ofv heat for varying the temperature, and upon a reversal of said departure producing a different effect.

2. The method of controlling the condition of a medium. which consists in producing upon a departure from a desired normal an effect which is afunction of the rate of change in said condition, of the departure of the condition from a predetermined magnitude and the increment of .lag 'ofsaid departure, controlling by said effect the'application of means for varying the condition, and upon a reversal of said departure producing another effect. V

3. The method of temperature control which consists'in testing the temperature, simultaneously adjusting the positions of a plurality of rate translators in accordance with said testing, se-

lecting one of said translators and transmitting the result ofsaid testing through the medium of said selected translator for the purpose of applying heat.

4. The method of temperature control which consists in testing the temperature, simultaneously' adjusting the positions of aplurality of rate translators in accordance with said testing, selectlng one of said translators and applying heat 40 at a rate determined by said selected translator.

5. The method of controlling the condition of a medium which comprises testing said condition, simultaneously moving a plurality of agencies having different transmission rates in accordance 45 with the indications of said testing, selecting one.

of said agencies and transmitting the result of said testing to a control agent at the rate determined by said selected agency. a

6. The method of temperature contrpl which 50 consists in testing the temperature, simultaneously moving a plurality of agencieshaving different transmission rates-in accordance with the indications of said testing, selecting one of said'agencies and transmitting the movement of said test- 55 ing to apply heat ata rate determined by the transmission rate of said selected agency.

7. An automatic system of temperature control comprising an instrument responsive to temperature changes, a plurality of members advanced 70 sociation with said members, and selective clutching means, operated by said instrument, .for

clutching any one of said members to said structure for movement thereby.

9. A system for the control of a medium com- 7 prising an instrument responsive to changes in the condition of said medium, a plurality of means advanced and returned by said instrument, a movable structure in association with said means and selectiveclutching means operated by said instrument for clutching any one of said means 5 to said structure'to control the condition of said medium.

10. In a control device an input and an output, means for moving said input, an integrating member, a'cam cut in accordance with the total devia- 10 tion' from normal of said input, a plurality of cams cut in accordance with the deviation of said input'per unit of time, means for engaging any one of said plurality of camsand means for moving said member in accordance with the conjoint 1 movements of said cams to efiect movement of said output.

11. A control system comprising a testing instrument, a movable member, means responsive to changes in a condition to be controlled, for

causing movement of said member, normally inactive means operated by said instrument for varying the relationship between said means and said member for causing additional movement of that the future relation between the condition and the movement of said member will be correct.

- 12. In a control system the method of moving the output in accordance with the movement of the input through the medium of a first cam, upon a reversal of trend, moving the output in accordance with the movement of the input through" the medium of a second cam, said first I and second cams operating to move said output at diiferent rates. 40

13. In a control system the method of moving the output in accordance with the movements of the input through the medium of a first means, translating said movement at a certain rate, upon a reversal of the trend, moving the output in accordance with the movement of the input through the medium of a second means and translating said second movement at a difierent rate.

14. In a control system the method of moving the output in accordance with the movement of the input through the medium of a first means, upon the reaching of a predetermined condition, moving the output in accordance with the movement of the input through the medium of a second means, said first and second means functioning to produce said movements at different rates.

15. In a control system the method of moving the output in response to movements of the input through the medium of a plurality of translating means, said means functioning at a plurality of.

variable rates.

' between said input and output, means for transmitting motion from-the first to the second shaft at one rate, means for transmitting motion from the first shaft to the third shaft at a different rate, and means dependent on the direction of rotation ofthe first shaft for selectively operating the output by the second and third shafts.

17. In a control system, an input and an output, a first shaft and a second and a third shaft between said input and output, means for transmitting motion from the first to the second shaft at one rate, means for transmitting motion from rate of change during the time that the trend of 1 said change is away from normal, and upon a reversal of said trend creating a different governing force during the return period of said temperature or pressure to the constant value.

19. That method of maintaining thetemperature or pressure of condition change and the rate of change to produce a governing force proportional to said integration, applying said governing force upon a departure from said constant, and upon a reversal of said departure applying a different governing force. 7 7

20. That method of maintaining a controllable condition substantially constant which is characterized by measuring said condition, .upon a departure from said condition creating a governing force which is proportional to the al ebraic sum of the condition change and the rate of change, applying said force to control said condition, and upon a reversal of said departure creata system substantially at a constant value which consists in integrating the ing a diiferent governing force and applying said different force to control said condition.

21. That method of maintaining a controllable condition substantially constant whichis characterized by measuring said condition, upon a departure from said condition creating a governing force which is proportional to the algebraic sum of the condition change and the rate of change, applying said force to control said condition, and at a-predeterminedperiod creating a different governing force'and applying said difv ferent force to control said condition.

22. That method of maintaining thetemperature or pressure of a system substantially at a constant value and in which during a departure from the constant value a governing force is created which is proportional to the integration of a plurality of condition changes and a plurality of rate changes, and'upon a reversal of said departure a different governing force is created.

23. That method of maintaining the temperature orfpressure' of a system substantially at a constant value which is characterized by the following steps: during a departure from the constant' value creating a governing force proportional to the summation of a plurality of condition changes, and upon a reversal of said departure and during a return to said constant creating a different governing force.

ANITA S. REYNOLDS. 

